The present invention relates generally to carts such as shopping carts and other similar devices utilizing casters or wheels which are used for temporary transportation of goods from one location to another, such as from a point of sale to a customer's car. The invention is particularly concerned with an anti-tilt or tip prevention device to limit tilting or tipping of carts or other similar wheeled devices.
Shopping carts are sometimes provided with security devices to deter shoppers and others from leaving a protected area with a cart, since theft or loss of shopping carts is a major problem for grocery stores and other types of business. Some carts are equipped with a locking device installed on one of the casters or wheels of the cart, typically at the front of the cart. The locking device is activated to lock the wheel against rotation when the cart is pushed over perimeter device. This impedes further movement of the cart since the locked wheel will drag on the ground. A security device and system of this type is described in U.S. Pat. No. 6,125,972 of French et al.
One problem with such security devices is that the locking caster or wheel can be circumvented by lifting it off the ground, thereby eliminating its deterrent effect. This can be done by tilting the cart rearwardly onto its rear wheels, thereby raising the front wheels (tilt), or by tipping the cart to one side so that it rests on one front wheel and one rear wheel (tip), with the front wheel which carries the locking device being raised from the ground.
Anti-tilt and tip devices are known but these are typically metal, U-shaped brackets which are permanently welded to the cart frame and which are designed to contact the ground when the cart is tilted or tipped. The frictional drag created by the contact of the metal bracket with the ground makes further motion of the cart difficult. However, the metal bracket will tend to damage many surfaces on which carts are generally used, such as ceramic, marble, tile, carpeting or the like. Additionally, the rigid metal bracket may cause injury to a person who inadvertently comes into contact with it, particularly since the bracket tends to develop an extremely sharp edge as a result of repeated dragging on the ground. Since the bracket is permanently attached to the cart, it is difficult to replace if it becomes worn or damaged.